How to determine what it takes to fully constrain sketch

[Noah_Katz]

No matter what I try, I'm not able to finish constraining the sketch.

What's maddening is that it was fully constrained until I changed some minor geometry, and an hour later (mostly because response time is ~10 s) I still can't finish.

Is there a way to interrogate geometry to show its remaining degrees of freedom.

There sure NEEDS to be.

[TrippyLighting]

I would probably break this sketch down into two or three sketches.

That will make it much more clear as to what is constrained and what not.

[Beyondforce]

Hey @Noah_Katz,

Interesting model, please check out the screencast and if you have more questions, please let us know:

Cheers / Ben
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Check out my YouTube channel: Fusion 360: NewbiesPlus

[Noah_Katz]

@Beyondforce

For context, this is the beginnings of a belt grinder:

The taper bushing and the motor were imported, so I couldn't build them in place.

Regarding sketch legibility, yes it's awful.

Perhaps you could help out by voting for my suggestion to improve it, which will be helpful even in smaller ones:

https://forums.autodesk.com/t5/fusion-360-ideastation-request-a/modification-to-display-environment-...

I did get carried away in including more future components than necessary, i.e. the shear plates represented by the rectangles with rounded edges.

However, I believe the bulk of the sketch consisting of the various wheels and belt path is necessary.

How else to know that the belt length is being maintained at its fixed length (72 in.)?

In sketch mode I can divide the circles at the belt tangent points so I can interrogate the length of belt in contact with the wheels.

I don't know how to do that in 3D.

[Noah_Katz]

Regarding my original question, I guess there's no way to interrogate what the remaining DOF are.

What we need is a "Show Free" command like other CAD has, which animates each unconstrained translational and rotational DOF.

Oh yeah, this was one of my first Ideastation posts:

https://forums.autodesk.com/t5/fusion-360-ideastation-request-a/show-free-degrees-of-freedom-of-sket...

Surprisingly, to me at least, it only got 3 votes.

I spend a good % of sketch time trying to figure that out.

[Beyondforce]

Hey @Noah_Katz,

I hope this will help you:

Cheers / Ben.

[Noah_Katz]

I'm traveling, will look at first chance I get

Thanks, Ben

[Noah_Katz]

@Beyondforce

Thanks for the screencast; very useful reminder to a newbie about reordering features.

Question: Starting at 2:24, why did you break the link of the plate sketch and move it?

All of the features to be added to it are based on the locations of things in the original sketch, and the relationship is now lost. So when you say I can then create holes etc in it, I wouldn't know where to put them.

[Noah_Katz]

I had a thought about how to declutter sketches and have less of them.

Using my current project as an example, after having determined the wheel configuration and belt path, I would start another sketch on an offset plane.

I would project necessary geometry to the new sketch and create the side plates, and repeat the process for the shear plates etc.

The projected geometry won't clutter up the sketch with its dimensions and presumably not burden the constraint solver.

What do you think?

[Beyondforce]

This is a good idea. This technique that you are working on, I like to call it the "Blue Print" technique.
I'm considering making a video about it for my YouTube channel. It can be powerful if you know how to use it.

What I'll do is, create a new component and put all those sketches inside that component. For each sketch I'll give an appropriate name, which will make it much easier to recognize.

When you are done, please attach the file and I'll check it out.

Good work.

[Noah_Katz]

Good morning 🙂

> What I'll do is, create a new component and put all those sketches inside that component.

Not sure I understand; I was thinking each sketch would be to create a different component.

Also, thinking more about your screencast, I'm not clear on why the layout sketch was moved to the beginning of the timeline.

[Noah_Katz]

Thanks, Ben, and I'll look forward to your blueprint video.

Could you let me know here where it is?

I'm off to bed.

[Beyondforce]

https://www.youtube.com/channel/UCv0LDps_1xX8NqkfiBK1LaQ

[cimbian]

Well, that was a really useful and informative screencast. Thank you!

Steve.

[Noah_Katz]

Thanks, Ben; and lots more good stuff to look at there